I've two comparators (say, CompA & CompB) in my design, whose outputs I take as interrupts by enabling the ComparatorBus interrupt. CompA is at a lower level (threshold) than CompB. Both are continuous time blocks.

I see that CompA works fine when the i/p exceeds the threshold. But it does not give an interrupt for the vice-versa. But, CompB works great for both cases. (You may see that they have different thresholds but the same input).

The red circle in the attached image indicates the absence of a transistion that has to occur when the input falls below the threshold or in other words that which executes an ISR.

Interrupt is generated only on rising edge of the comparator output. You are getting on CompB; this is due to the noise near the threshold. I would suggest to route the comparator outputs to a pin (through DigBuf) and then see the outputs.